Kotlin vs Java — Which is Better for Android App Development?

Every year, the Android market becomes more and more saturated with a huge variety of apps. Mastering the right tool is key in not only developing but also bringing your app into the spotlight. Today, we’ll try to focus on two most popular Android-centric programming languages in a direct Java vs Kotlin performance comparison.

Before we get into it, we’d like to note that this guide is written not only for those who are already familiar with either language but also for people who are looking to find the right developers for their next project.

Without further ado, let’s see what Kotlin and Java have to offer.

Kotlin as a modern programming language

Kotlin was introduced back in 2016 after being announced even half a decade before that. It’s a great example of a modern and statically typed programming language that runs on the Java Virtual Machine (JVM). 

The idea behind making Kotlin was to design a language that is fully interoperable with Java. This means that you can easily integrate Kotlin code into existing Java projects, which, as you can see, is the first advantage of using it for an Android project.

Simply put, Kotlin is known for its concise syntax, reducing boilerplate code, and making development more efficient in general.

What advantages and disadvantages does Kotlin offer?

If we take a closer look at all the pros that come with Kotlin, we’ll notice some features that are also present among other languages. This means that Kotlin is a quite convenient programming language that offers the best out of the majority of other languages.

Kotlin offers:

• Concise syntax — Something that makes Kotlin stand out is its syntax — A syntax that is more streamlined, which ultimately results in reducing the need for boilerplate code. This is a huge advantage as it makes Kotlin a language that gets straight to the point.
• Null safety — The dreaded NullPointerExceptions here are completely eliminated by enforcing null safety at compile time. Another bonus as they are often the cause of unexpected crashes in Java.
• Interoperability — Imagine having two sets of Lego blocks that fit together perfectly. As briefly mentioned above, Kotlin is fully interoperable with Java. This means that you can smoothly integrate Kotlin code into existing Java projects.
• Coroutines — Writing asynchronous code in Kotlin with coroutines is like having a well-organized to-do list. A list that lets you pause one task and come back to it later without forgetting where you left off. That way, as a developer, you can just simply write non-blocking code which ultimately leads to more responsive applications.
• Modern features — Kotlin offers some more advanced tools compared to some other languages. Tools like functional programming, higher-order functions, and lambda expressions.

And what about its downsides?

• Learning curve — This is a con present within many other modern languages. Even for developers familiar with Java, Kotlin's syntax and features may still require some adjustment. Overall, learning Kotlin isn’t that tedious.
• Community support — While still growing, Kotlin’s community is notably smaller compared to Java's. This ultimately means fewer resources for troubleshooting, among other things. However, the amount of help you can find online when it comes to Kotlin is far from being abysmal.

What key features does Kotlin have?

Here’s a quick overview of some of the most notable features that make Kotlin stand out:

• Extension functions — Kotlin allows you to extend existing classes with new functionality without inheriting them.

A more colorful explanation would be that Kotlin allows you to build a house with various different features. You can add practically anything you’d like, a pool, a garage, a football field. All without needing to rebuild them from scratch.

• Data classes — Kotlin simplifies the creation of data classes by automatically generating essential methods like equals(), hashCode(), and toString().

If this seems way too bland and generic, just try to imagine writing a list of friends' names, addresses, and phone numbers. Normally, you’d have to write out all their details every time you want to use them. But with Kotlin, it’s like having some sort of an efficient notebook that fills in all those details for you automatically whenever you need them.

• Smart casts — Kotlin's compiler automatically handles casting which reduces the need for explicit type checks. A good analogy here would be having a box full of different toy animals. Every time you pull one out, you know right away if it’s a duck or a frog without having to check. Kotlin does something similar by automatically recognizing the type of information it’s dealing with, so you don’t have to.

Kotlin in Action — examples

Here's an example of Kotlin’s concise syntax:

val greeting = "Hello, Kotlin!"

println(greeting)

In just two lines, you can declare a variable and print it, which is both quite convenient and more efficient.

Java as Kotlin’s predecessor

Java is an almost thirty-year-old programming language now as it was released in 1995. It’s without a doubt one of the most popular and established programming languages in the world. 

Java was developed by James Gosling at Sun Microsystems, and it made an impact right away with its write once, run anywhere philosophy. It’s a general-purpose, object-oriented language known for its portability across different platforms, thanks to the aforementioned JVM (Java Virtual Machine).

Pros and cons of using Java

Let’s see all the positives of Java as a programming language:

• Mature ecosystem — Java is renowned for its impressive ecosystem of not only libraries and frameworks but also tools that support development across various domains. While using an older language might seem slightly impractical, we feel like there are still many positives to opting for Java.
• Cross-platform — A quite practical side of Java is Its platform independence. This means that, as a developer, you could easily run it on practically any device or operating system with a JVM.
• Java’s performance — Compared to some other languages, Java’s performance is stable and reliable. This is always a huge bonus for large-scale applications.
• Strong community support — Java has one of the largest developer communities, as it offers extensive documentation and support. You could probably even stumble upon a thread on a random forum from 20+ years ago that could help you resolve your current problem. Also, there are numberless subreddits that are all committed to helping developers not only resolve issues with Java but also completely master it.

And here are the negatives:

• Verbose syntax — Java's syntax can be, to put it simply, a bit more verbose. It requires more lines of code to finish a task. Compared to Kotlin this might seem somewhat impractical as sometimes it takes a bit more time to work on a project.
• NullPointerExceptions — Java allows null assignments by default. This can lead to runtime exceptions if not handled properly and it ultimately might make everything slightly more tedious.

And what key features does Java have?

The features below are what makes Java stand out, even now in 2024:

• Object-oriented — Java is an object-oriented language. This means that it provides a clear structure for programs. Why is this a standout feature? Mostly because it makes it easier to manage large codebases which is fairly convenient for developers.
• Platform independence — Its code is compiled into bytecode that can run on any Java Virtual Machine. It ultimately makes Java highly portable.
• Checked exceptions — Java enforces exception handling at compile time. This results in Java producing an error-free code, which is naturally a quite useful feature both for those who are new to Java and those who are already quite familiar with it.
• Multithreading — It supports multithreading. This allows concurrent execution of two or more parts of a program for maximum CPU utilization.

Java in action — examples

Here’s a simple Java example:

String greeting = "Hello, Java!";

System.out.println(greeting);

Now we have a clearer picture of the direct Java vs Kotlin comparison.

Kotlin vs Java — Comparison table

When you should use Kotlin

As briefly mentioned in the intro, if your project is focused on Android development and you’re looking for a modern language with some essential features like null safety and coroutines, Kotlin is the way to go. 

When you should opt for Java

Java still remains a more-than-a-solid choice for projects that rely on optimal performance. It’s particularly well-suited for large-scale enterprise applications and backend services. Or, basically, any scenario where a stable language is crucial. In our honest opinion, The Kotlin vs Java performance debate should be kept to a minimum.

FAQs

1. Java vs Kotlin: Which is better for Android development?

While both are Android-related programming languages, Kotlin is considered a preferred option due to its modern features. Regardless of that, Java still remains a solid choice, especially for older systems.

2. Is Kotlin replacing Java?

Kotlin has been gaining some traction in the past couple of years, but Java is far from becoming a relic. One thing is for certain, both can be useful, but it all depends on the project.

3. What does Kotlin vs Java performance comparison look like?

Many developers would agree on one thing. Both Kotlin and Java perform similarly. While Kotlin's features may slow compilation slightly, runtime performance is nearly the same.

Build your next mobile app with Tapptitude

Choosing the right programming language is the first step in building a successful mobile app. We know that sometimes this process can be tedious. But, don’t worry, that’s where we come in.

Here at Tapptitude, we specialize in one thing — Delivering high-quality projects that suit your business in the best possible way. Regardless of whether you opt for Kotlin, Java, a combination of both, or even something completely different, we can assure you that our experienced team is here to help you every step of the way.

Let’s try to bring your vision to life. The Kotlin versus Java dilemma shouldn’t be an issue anymore.